Electrical apparatus



Dec. 15, 1931. ,1. A. PROCTOR ELECTRICAL APPARATUS Original Filed June4, 1921 Patented Dec. 15, 1931 UNITED STATES PATENT OFFICE JOHN A.PROCTOR, OF LEXINGTON, MASSACHUSETTS, ASSIGNOR, BY MESNE ASSIGN MENTS,TO GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK ELECTRICALAPPARATUS Original application led June 4, 1921, Serial No. 475,144, nowPatent No. 1,510,341, dated September 30,

1924. Divided and this application led February 28, 1923.

This invention relates to switches for use in high potential work suchas in radio transmitters and receivers and in power factor work.

This application is a division of Serial No. 475,144, filed June 4,1921, issued as Patent No. 1,510,341, September 30, 1924. No suitableswitch hasbeen heretofore devised which yis capable of withstanding,when open, the

normal Working voltage of a radio transmitter, say 50,000 volts, and atthe same time to have the contacts close enough together so that theywill work sutliciently quick and be sufficiently sensitive to open andclose during the brief intervals between successive actuations of thetransmitting key.

Also in power factor work, a reliable high voltage disconnecting switchhas not been available for use in connection with static condenserinstallations.

In power factor work, an economical, reliable high voltage disconnectingswitch has not been available for use in connection with staticcondenser installations.

'Ihe power factor of a high voltage system varies with the load on thesystem. It is, therefore, of great importance to be able to control theamount of condenser current placed across these lines in such a manneras to provide the best power factor for conditions of load on thesystem. In a power` factor' 'static condenser installation across afairly low voltage line, the amount of correction may be varied byswitchingcondensers on and off the line, using oil or other switches ofstandard design. However, if condensers are placed directly in the highpotential line, the standard switching means now on the market is notsuitable for use in continuously making and breaking circuits connectedto them, due to the destructive arcing accompanying their operation. Oilswitches of proportions ample to take care of the disconnection andre-connection of apparatus on high potential lines are too eX- pensiveto warrant their use for this work. Disconnecting switches, therefore,form an important element of the static condenser power factor s stem.Inasmuch as the hourly variation o power factor on a high volt- SerialNo. 621,728.

-the ability to successfully andcheaply disconnect at will banks of highvoltage condensers. Assume, for example, a high voltage line withoutload. The line would simply be carrying charging current or have a verylow leading power factor. As the substa.- tions take off load, the powerfactor would increase and still be leading. Since substation loads areusually at a lagglng power factor, the capacity reactance of the line isultimately neutralized by the inductive reactance of the load. A pointis usuall reached within a range of 10% to 75% of the full output of thesystem when the power factor is approximately unity. As more load withlagging characteristic is added to the line, the Whole system becomeslagging and the power factordrops. The power factor may be restored byadding a condenser at the consuming end. It will be appreciated that ifthis is done and the consumers cut off their load and leave thecondenser connected to the line for light loads on the line, the powerfactor will be low and leading. The main objection to this is not thatthere will be high losses on low loads, but is primarily one of poorvoltage regulation. If the condensers are cut out of circuit in steps asthe load is varied, the power factor can be maintained at a high valueover a considerable variation in load. The importance of correctioncontrol increases with the length and voltage of the line.

In the present invention, it is my plan to provide vacuum switches forreplacing the high voltage oil and other forms of switches now in use. Iprovide relatively movable contacts which operate in a vacuum, thecontacts being enclosed in a bulb from which air has been exhausted.Means is also provided to prevent the heating of the glass or otherfusible material used in the construc tion of the apparatus due to thecutting of- :soA

the glass by the electric lines of force developed at high potentials.

An object of the present invention is to provide constructions of theabove type in which the losses are at a minimum.

In particular, the object of the invention is to provide a condenser orhigh voltage switch which will be comparatively cheap and economical tobuild and which is efcient and durable.

Another object of the invention is to provide a high voltage switch inwhich there will be very little loss or sparking when the switch isopened,lwhereby high voltage circuits can be quickly made and broken.

. Another object of the invention is to so vform the terminals of theswitch that the form of vacuum switch having a single throwv contactembodying the present invention.

Referring to Figure 1, there is illustrated a switch S having a casingor bulb 1 which ma comprise any fusible dielectric materia such vas highmelting point glass, from the interior of which air may be exhausted.Secured at opposite ends within the ca sing 1 are metal disks or shields2 and 3. A' metal conducting rod 4 is supported by the disk 2 andterminates adjacent the enlarged central ortion of casing 1 in a-contact5, the rod 4 eing electrically connected to a wire conductor 6 sealed inthe glass of the casing 1 in the manner herinafter described. Supportedby the metal disk 3 at the opposite end of the casing 1 is a metalconducting rod 7 which terminates `at its inner end in a iiexible metalspring member 8 having a contact 9 at its free end adapted to engagewith the contact 5. The rod 7 is conductively connected to a wire 10sealed in the glass of the casing 1 as hereinafter described. Projectinginwardly towards the contacts'5 and 9 is a third conductive rod 11supported within the casing 1 by means of a-frame 11a and arranged at anangle to rods 4 and 7. The rod 11 terminates in a contact 12 betweenwhich and the contact 5 is interposed the contact 9, the contact 9 beingadapted to alternately engage the contacts 5 and 12. The rod 11 iselectrically connected to a wire 13 sealed in the glass casing 1 and'extending therethrough.,

The contacts 5, 9 and 12 may comprise vsome high melting point metal andvgood conducting'metal such as tungsten which will not melt under thehigh heat developed in the switch during service nor at suchtemperatures give oil gases which would impair the vacuum.

In order to localize the electric elds both inside and outside of thecasing 1 in high voltage service and to maintain such field parallelwith the casing 1 at all points to prevent the cutting of the casing bythe lines of force which would otherwise heat the casing, I use the twometal disks or shields 2 and 3 within the casing at opposite ends andwhichI are electrically connected to the rods 4 and 7, as the rods mayhave a dierence of potential of the order of 50,000 volts. Upon theoutside of the casing 1 at opposite ends, I place metal caps or shields14 and 15, which may serve as 'terminals and which are secured to theends of the casing in any suitable manner and are flared out away fromcasing 1 and rolled at -their edges 16 to prevent brushing and .con-

centration of the electric field and space the edges of the caps fromthe casing. In like manner, the disks 2 and 3'are rolled up at theiredges 17 to prevent concentration of the field. The caps 14 and 15 areelectrically connected to the disks2 and 3 through con ductors 6 and 10,and are therefore at the same potential as the disks. Centrally arrangedwithin the casing is a cylindrical metal shield 18 which has itsopposite edges rolled at 19 and spaced from shields 2 and 3 for thepurpose specified and is provided with a hole 20 through which the rod11 extends and from which it is spaced. Arranged concentrically withtheshield 18 upon the outside o the casing 1 is a metal shield 21 providedwith an opening 22 through which the conductor or lead 13 passes andwhereby it isv 9 alternately engages contacts 5 and 12. v

This means in the present embodiment of the invention as disclosed inFig. 1 comprising a soft iron armature 24 secured to the flexiblesupport 8 and movable between spaced soft iron pieces 25 vsecured to theshield 18 and providing a magnetic path. I-he contact 9 is actuated froma point exterior of the casing 1 by magnetic means such as theelectromagnet 26, which is connected in a circuit containing a suitablesource of energy as hereinafter described, and a permanent magnet orelectromagnet 27 which tends normallyto draw the contact 9 intoengagement with the contact 12, the electromagnet 26 when energizedopposing the magnet 27 and overcoming the force thereof to bring thecontacts 5 and 9 together. The iron pieces 25 provide a magnetic pathbetween-the 4outside magnets and armature 24. As more fully describedhereina-fter, the air has been exhausted from within the casing 1whereby the contacts 5, 9 and 12 operate in a vacuum in the mannerhereinafter more fully described.

The form of switch disclosed in Fig. 1, is particularly adapted for usein connection with radio transmitting and receiving apparatus as fullydescribed in my previously mentioned Patent 1,510,341. For this purpose,the specific embodiment of switch illustrated is especially adapted. Theelectromagnet 26 comprises a coil 28 and a circuit 29 having a battery30 therein for energizing the magnet. This circuit 29 is completed bymeans of a contact 31, which is spring-mounted at 32, and engages withthe usual key 35. When the key 35 is released, the permanent magnet 27then automatically draws the contact 9 into engagement with contact 12.By operating the contacts 5, 9 and 12 in a vacuum the dielectricstrength of the vacuum is such that the contacts 9 and 12 may be placedvery close together and still be capable of withstanding withoutbreakdown or the slightest leakage the high potentials impressedtherebetween.

In order to prevent high losses in the glass of casing 1 due to theintense electric fields generated in the high voltage circuits of thischaracter as disclosed in Fig. 1, the shields 2, 3 and 18 are locatedupon the inside of the casing 1 while the shields 14, 15 and 21 arelocated upon the outside of the casing. By utilizing the said shields,the electric fields that are set up in and around the switch S in highvoltage service instead of cutting the casing 1 are substantiallyparallel therewith,extending between the disk 2 and the shield 18, onthe one hand, and between the disk 3 and the shield 18, on the otherhand, within the casing 1, and on the outside of the casing extendingbetween the cap 14 and shield 21 and cap 15 and shield 21. By flaringout the edges of the shields 14 and 15 and shield 21 upon the outside ofthe casing, a path is provided between them outside of the casing forthe electric field which is spaced from the glass. The glass casing 1provides the proper leakage distance between the caps 14 and 15 otopposite potential located at opposite ends of the casing. The ieldwithin the casing 1 is strongly localized therein by means of the innershields 2, 3 and 18 whereby the lines of force are prevented fromcutting the glass casing. The iield on the outside of the casing islocalized and spaced from the casing between the caps 14 and 15 andshield 21. The shields 2, 3 and 18 within the casing are at thepotential of shields 14, 15 and 21 respectively outside of the casing;hence no field exists across the casing between adjacent or opposingshields.

In order to position or place the metal parts of the present inventionwithin the casingl, during construction, one or both ends of the casingare lett open so that the parts may be inserted. The intermediate leads13 and 23 extending through the glass are then sealed in. The end orends are then sealed up and the leads through the ends sealed in. Aglass tube is left extending into the casing and at some accessiblepoint, through which tube the high degree of exhaustion can be obtained.After exhaustion, the tube through which the exhaustion has taken placemay be melted from casing 1 and sealed up.

The order of vacuum or exhaustion which exists in a switch of theabove-described type should be extremely high, such that no appreciablegas ionization takes place to cause losses while the apparatus .is inoperation, which condition .is obtained, for example, by a pressure ofthe order of a millionth of a millimeter of mercury. Such exhaustion maybe obtained by any well-known means, such as a Gaede or molecular pumpor Langmuirs condensation pump.

All'materials inside the casings of such vacuum switches are to besuitably treated to remove gases (occluded or otherwise) according toany of the well-known processes in use for the production of high vacuumapparatus. Such treatment may consist, for example, in initially, beforeassembling in the casing, treating these materials to remove gaspreliminarily, as by heat of the order of the melting point of thematerials or by heat of a lower order for a longe-r period. One methodofremoving such occluded gases is to place the metal parts in an ovenand heat them to a high temperature, of the order of 500, to 1100o C.,for a suiiicient time to remo\'e the gases. In addition, it isadvisable, after assembling in the casing, which may be of high meltingpoint glass, to subject the contained materials and casing to furthertreatment t0 remove any residual or occluded gases, while evacuation istaking place. This final treatment may consist of heating in an oven atthe highest temperature the glass will stand,-say in the neighborhood of500o C., evacuation taking place while being heated in the oven. Thecasing or bulb is then sealed ofi".

Another final treatment may be the well- 115 known method of removinggases from metals by inserting the metallic portions and casing in ahigh frequency magnetic alternating iield of a suitable intensity duringexhaustion. In this final treatment, the en- 120 tire device, whileundergoing exhaustion, may be placed within the field of a coilcarryinghigh-frequency current. This heats the metal parts, inside the casing,thereby driving oil and removing gases before the 125 device iscompletely exhausted, and then sealed 011'.

The materials used in the vacuum switches herein described should be ofsuch a nature that the gases may easily -be removed by 130 Surroundingthe end of the tube 55 having the above-described processes. Therefore,in constructing them, nickel, tungsten, molybdenum, pure iron,preferably plated with cobalt, or rolled steel should be used whereverpossible in constructing all parts.

'Ihe conductors-6, 10, 13 and 23 may be of platinum if so desired,especially when casing 1 is of glass, on account of the similarco-eiiicients/of expansion of glass and platinum, and,4v in anyinstance, any well-known seal, such as used with'high vacuum devicessuch as X-ray tubes, thermionic devices, and the like, may be used forbringing the conductors out and maintaining the high vacuum necessary inthe present invention.

Referring to Fig. 2, I have illustrated a modified form of vacuum'switchS which is described and specifically claimed in my divisionalapplication Serial No. 259,880, filed March 7, 1928. This switchcomprises a casing 55 of insulating material having within the same atone end a metal support- 56, terminating in a spring-or cushion 57having a contact 58 thereon. Mounted in the opposite end of the casing55 is a metal support orguide 59 having at its lower end a springbuii'er or cushion 60. Slidably mounted within the guide 59 and betweenthe cushions 57 and 60 is a rod 61 havingat its inner end a contact 62co-operating with contactJ 58. At the opposite end of rod 61 is a softiron armature 63 whereby the rod 61 and its` contact 62 may be actuatedin the manner hereinafter described. The parts within the casing 55 maybe assembled, treated and evacuated in the manner above-described inconnection with Fig. 1, and the operation of the break or relay issubstantially like that disclosed. in Fig. 1, although in thisembodiment the number of contacts have been reduced and spring' meanshave been provided for taking up the shock of impact of the relativelymoving contacts. These contacts, which may be of silver or similar goodconducting metal, like the contacts of Fig. 1, operate in 'a vacuumwhereby their separation and contact malbe rapid and quick whilemaintaining high insulation resistance between them when opened byreason of the high dielectric properties of the vacuum.

movable armature 63 are a pair of solenoids or electromagnets 64 and 65,adapted when energized to alternately close the contacts 58 and 62 andseparate them. .These switches are of general application and areespecially adapted for use in power factor work. In

' the illustration of Fig. 2, the switch S is so arranged that it may beremotely controlled. For this purpose, I have illustrated the controlkey 66. in series with the line L, which, when it is depressed,energizes a solenoid 67, which in turn actuates a multiple switchingdevice or rod 68 by reason .of its attraction for a softmetal core 69secured to the rod 68.

The rod 68 is slidably mounted in suitable guides 70, and is constrainedto move in one direction by means of a spring 71, the solenoid 67actuating rod 68 in the opposite direction upon the'depression ofthe key66, the spring actuating the rod upon the release of the key 66. The rod68 controls the switches '72, 73. Vhen the key 66 is depressed to closethe circuit L, the switch 72 isy opened, and then the switch 7 3 isclosed. In the position illustrated in the drawings, the switch 72 isclosed, the other switch being open, thereby energizing the solenoid 64which is connected to the line by lead 76 through switch 72. Upon thedepression of key 66, switch 72 opens, de-energizing the solenoid 64,and then yielding switch 73 closes, energizing the solenoid connected tothe line through conductor 77 to rapidly open the contacts 58 and 62 bythe attraction of the solenoid 65 for the armature 63. The contacts 58and 62, althoughclose together when open, are sutilciently insulated bythe vacuum dielectric to prevent sparking or brushing.` On the otherhand, these contacts 58 and 62 are closed whenever the key 66 isreleased. The form of switches disclosed in Figs. 1 and 2'arecharacterized by rapidity of opening in a vacuum and are especiallyadvantageous for use in handling high potentials. The shields disclosedin Fig. 1 may be incorporated in the break switch disclosed in Fig. 2.

The construction and method of assembly of the vacuum switch S of Fig. 2may be accomplished' just like that described in connection with Fig. 1,and the materials should be such as above enumerated. In Fig. 2, one ofthe solenoids for actuating thecontact 62 may be replaced by anyequivalent means such as a'spring. As illustrated, the impact of thecontact 62 is taken up and resisted bv the springs 57 and 60 whereby jarupon above described provide compact, cheap, ef-

i'icient means for controlling the high potentials in circuits wherethey are used. These vacuum switches are highly sensitive and with veryslight separation of contacts maintain the circuits electrically open,notwithstanding the high potentials existing in their neighborhood.Furthermore, the cases are' iso amplji7 protected by the static shieldsemlo e p Iii is to be understood' that the invention is not limited tothe embodiments and fea- 5 tures specifically shown and describedherein, but that such embodiments and features are subject to changesand modifications without any departure from the spirit of theinvention.

I claim j 1. In a switch, a casing of insulating material, relativelymovable contacts mounted within the casing, leads from said contactsextending through the casing, means for making and breaking the circuitat said contacts;`and shields associated with said leads and casing toprevent the 'heating of and losses in the casing by the electric field.

2. In a high duty dielectric switch, a casing havingy an enlargedcentral portion from which air has been exhausted forming a vateuum andprovided with conductors sealed 1n the opposite ends of said casing andterminating adjacent the enlarged central portion thereof, a. pair ofrelatively movable high melting point contacts mounted upon the ends ofsaid conductors within said casing in the vacuum, said' contacts beingsubstantially free of residual or occluded gases whereby the formationof gases within the casing by heating of the contactsl bythe current isprevented and the vacuum 1s maintained, and protective shieldsassociated with the sealed in portions of said conductors,

3. In a switch, an air tight casing from which air has been exhausted,cooperating circuit controlling contacts within said casing one beingmovable, a member of magnetic material secured to said movable contact,a second member of magnetic material mounted within the casing in spacedrelation with the first member and means outside of the casing formagnetizing said magnetic member to operate said movable contact.

ing of insulating material, relatively movable contacts arranged thereinintermediate the walls thereof; leads for said contacts extending thruthe interior of the casing to and thru the walls thereof at Vwidelyseparated points; metal static shields located inside the casing in thevicinity of the points of passage of said leads thru the casing walls;and metal static shields located outside the casing in the vicinity ofthe interior shields; the neighboring interior and exterior shieldsbeing electrically connected with the adjacent contact leadi andreducing cutting of the casing wall by high tension lines of force.

5. The improvement substantially-as specified in claim 4 but furthercharacterized by the fact that the casing is oblong and the two pairs ofshields are located respectively at the 65 end of the casing, providinga wide spacing 4. A high tension switch comprising a casbetween theopposite terminals of high poy tential difference.

6. The improvement substantially as specified in claim 4 but furthercharacterized by the fact that the exterior shields are spaced from thecasing, thereby localizing'the exterior field away from the casing.

7 A high vacuum switch comprising an airtight casing having an enlargedcentral portion and provided with conductors sealed in the opposed endsof said casing and terminating adjacent the enlarged central portionthereof, relatively movable contacts mounted upon the free ends of saidconductors for separation within said casing, said contacts beingsubstantially free of residual or occluded gases and the said casing eX-hausted to such a high degree of vacuum that no appreciable gasionization takes place While the switch is in operation whereby theswitch may control a high potential circuit with a relatively smallseparation of the contacts, means for opening and closing said contacts,and protective shields associated with the sealed in portions of saidconductors.

8. A high vacuum switch comprising an air-tight casing having anenlarged central portion and provided with conductors sealed in theopposite ends of said casing and terminating adjacent the enlargedcentral portion thereof, means including a tungsten contact mounted onthe free end of one of said conductors and a cooperating contact mountedvon the free end of the other conductor for making and breaking acircuit within said casing, said contact means having been treat. ed toremove residual or occluded gases therein and the said casing exhaustedto such a degree that no appreciable gas ionization takes place duringoperation of the switch means for operating said contact means toengageand disengage the contacts, and protective shields associatedVwith the sealed in f portions of said conductors.

9. A high potential, high vacuum switch,A comprising an air-tight casinghaving an enlarged central portion and provided' with conductors sealedin the opposite ends of said casing and terminating adjacent the'enlarged central portion thereof, a pair of relatively movable.contacts mounted on the free ends of said conductors to be separatedwithin said' casing, said'contacts and all parts and surfaces within thecasing having been treated to remove residual or occluded gases and saidcasing exhausted to provide a vacuum of the order of one millionth of amillimeter, whereby the formation of gases within the casing isprevented and vacuum is maintained during operation of the switch, andprotective shields associated with the sealed in portions of saidconductors.

JOHN A. PROCTOR.

